Abstract Sepsis and trauma are two of the most catastrophic challenges, and result in the rapid and immediate reprioritization of host protective immunity. We have used terms like ?genomic storm? and ?cytokine storm? to summarize the host immunological changes that accompany tissue damage or microbial infection. Controversially, we have argued that both trauma and sepsis are diseases of the bone marrow, and that ?emergency myelopoiesis? defines the bone marrow and secondary hematologic tissue responses to trauma and sepsis. We have spent the past decade characterizing both the mature blood and tissue immunological response, as well as the hematopoietic response in bone marrow, and we were the first to describe the expansion of immature myeloid populations in sepsis. We have also demonstrated the importance of beta adrenergic stimulation on hemato- and myelopoiesis. NIGMS-funded investigators in our group have been exploring the effect of age (very young and very old) on the hematopoietic response. For the past decade, we have used a Becton-Dickinson LSRII flow cytometer to phenotype human blood and bone marrow leukocytes, and murine blood and tissues following severe trauma and sepsis. Because human trauma and sepsis occur 24/7 (especially late at night and on weekends), the instrument is being used at all times of night and day, and is often required on short to immediate notice for samples from human trauma and sepsis. This precludes sharing an instrument with other entities. We have been informed that the current LSRII is at the end of its scheduled life-span and Becton-Dickinson will no longer service the instrument or provide replacement parts. We are therefore requesting funds to partially offset the cost of a new LSR-Fortessa, four-laser, 16 color flow cytometer as a shared instrument among five NIGMS-funded investigators. The department of surgery will contribute up to $80,000 towards its purchase. The instrument will replace the LSRII and will be available to all current LSRII users. The new instrument will provide additional capabilities which will increase our capacity to more precisely phenotype leukocyte populations, going to 16 analytes (colors) versus the current eight, making it possible to more accurately identify our leukocyte populations. In addition to its ability to better characterize the immature myeloid and hematopoietic stem cell populations, its sampling speed and additional colors will reduce significantly the labor involved in sample preparation and analysis. The LSRII has served us well for over a decade, but the new instrument is essential to maintain existing productivity and to improve the analytical capabilities of multiple NIGMS awardees.